This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary objective of this project is to enhance our understanding of the mechanisms of increased bone resorption, which accompanies estrogen deficiency. Bone resorption parameters have been compared between control females six months of age, ovariectomized females (OVX), females receiving hormone replacement therapy (HRT), and females receiving a calcium channel antagonists (Diltiazem, Nifedipine, Verapamil), or females receiving a combination of the two agents.